I think Neal sent Hook the message and told him to go get Emma but not to tell her. If she knew Neal was in trouble she’d go after him (see: Neverland arc). So Hook is keeping secrets about Neal, who is working as a double agent for Zelena
Agreed. If Zelena has some measure of control over Neal, was perhaps keeping him prisoner, (in both FTL and in SB, maybe he was being kept in the house and managed to get out and then went to bust Rumple out too), then he’d know about her Curse plans, but may have still had enough freedom to have been able to get the message to Hook via bird. He may even have had access to the stuff to make the memory potion if he could get into Zelena’s stash. If so, then I could see Neal adding a “PS. Don’t know if/when I’ll be able to get free, so don’t tell Emma what’s up with me when you see her.”